Defibrillator paddle stand including means for applying electrocardiographic electrode paste to paddles and permitting paste conductivity tests



H. KARSH DEFIBRILLATOR PADDLE STAND INCLUDING 'MEANS FOR APPLYING ELECTROCARDIOGRAPHIC ELECTRODE PASTE TO PADDLFJS AND PERMITTING PASTE CONDUCTIVITY TESTS Filed Feb. 27, 1967 FIG.4

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RO ATTORNEY United States Patent 3,467,863 DEFIBRILLATOR PADDLE STAND INCLUDING MEANS FOR APPLYING ELECTROCARDIO- GRAPHIC ELECTRODE PASTE TO PADDLES lNsDsPERMlTTlNG PASTE CONDUCTIVITY T Herbert Karsh, Lexington, Mass., assignor to Lexington Instrument Corporation, a corporation of Massachusetts Filed Feb. 27, 1967, Ser. No. 618,893 Int. Cl. G01r 27/02; A61b /04 US. Cl. 32465 6 Claims ABSTRACT OF THE DISCLOSURE This invention relates to electrocardiology and more particularly to a novel stand for testing and storage of defibrillator paddles.

It is known that in certain cardiac conditions the operation of the heart is characterized by an uncoordinated activity or arrhythmia known as fibrillation. Atrial fibrillation is a rather common condition which ordinarily does not endanger life. On the other hand, ventricular fibrillation is indicative of a potentially fatal medical emergency. Electrocardiographic traces of characteristic ventricular fibrillation display a typical undulatory pattern which has replaced the normal heart-beat complex Waveform. Resuscitation of patents exhibiting ventricular fibrillation can be accomplished with a device known as a defibrillator. Essentially this device comprises means for generating short (e.g. about 55 millisec.) pulses of high electrical energy, typically 400 watt seconds, and a pair of electrodes known as defibrillator paddles, each having a substantially flat, electrically-conductive surface, usually of stainless steel or the like. These electrodes are applied in spaced relation in contact with the skin of the patients chest and the high energy pulse is discharged between the electrodes. Frequently, when the heat is fibrillating or is in the state of cardiac arrest following fibrillation, one or more shocks in this fashion serve to restore the heart to substantially normal operation.

Generally, the defibrillator generator includes means for monitoring the shock, usually in the form of a meter with a needle, the needle deflection indicating that an electrical discharge is occurring.

It will be apparent that the use of defibrillator devices is almost always under emergency conditions where time is critical. Before applying defibrillator paddles, it is customary to coat the conductive surface of each paddle with an electrocardiographic electrode paste such as the conductive paste sold by Sanborn division of Hewlett- Packard Co. (Waltham, Mass.) under the trademark Redux. This paste, usually an NaCl gel, reduces contact resistance by providing a low impedance path between the paddle and the patients skin. Failure to apply the paste can result in serious injury from burns from electrical arcs which tend to form due to the high electrical power of the discharge. If the paste is not imme- "ice diately available, a patients life can be seriously endangered or he may be exposed to the risk of serious burns. Even when the defibrillator paddles are properly coated and applied and the defibrillator turned on, if the latter is not operating properly there is usually not suificient time to either repair the defibrillator or to replace it with an operative device.

It is, therefore, a principal object of the present invention to provide a novel test stand for defibrillator paddles which allows the operation of a defibrillator to be quickly pre-tested, and also insures that the defibrillator paddles will be properly coated with conductive paste.

Other objects of the invention will in part be obvious and will in part appear hereinafter. The invention accordingly comprises the apparatus possessing the construction, combination of elements, and arrangement of parts which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the present invention, reference should be had to the following detailed description taken in connection with the accompanying drawing wherein:

FIG. 1 is a perspective view, partly in phantom, of apparatus embodying the principles of the present invention;

FIG. 2 is a perspective view showing the apparatus of FIG. 1 in operative relation to a defibrillator and other elements;

FIG. 3 is a fragmentary, cross-sectional view taken across a well of an embodiment of the present invention;

FIG. 4 is a fragmentary, cross-sectional view taken along the line 44 of FIG. 3;

FIG. 5 is a cross-sectional view in fragment through an alternative structure of the present invention; and

FIG. 6 is a cross-sectional view taken along the line 6-6 of the embodiment of FIG. 5.

The foregoing and other objects are generally effected by the provision of a paddle stand generally comprising means defining a pair of spaced apart containers or wells dimensioned and shaped so that the conductive surface of a defibrillator paddle can be placed in each well. Ther is further provided a chamber having an entrance port adapted to be coupled to a supply of conductive electrode paste, and means defining a paste path or conduit between each well and the chamber.

Referring now to FIG. 1 there is seen a stand embodying the principles of the present invention and comprising a base element or slab 20 preferably formed of a dielectric material such as polymethyl methacrylate, polyvinyl chloride, or the like. Typically, slab 20 is in substantially rectangular form and is of finite thickness, for example, measuring 12" x 6 x 1". As means for containing defibrillator paddles there are disposed in the upper surface of slab 20 a pair of dished out portions or wells 22 and 24, typically circular and extending downwardly into slab 22 a short distance, for example /2". Disposed within slab 20 preferably between and equidistant from wells 22 and 24 is a central hollow chamber 26. An entrance tube or port 28 is provided extending from the top surface of slab 20 into chamber 26. Electrically conductive paste suitable for use with defibrillator paddles is commercially available in squeeze tubes having threaded caps for closure. Therefore, in a preferred embodiment, port 28 is tubular and is dimensioned and interiorly threaded so that the neck of a squeeze tube containing conductive paste can be screwed into sealed engagement with the port.

First hollow conduit 30, preferably tortuous in configuration, is provided for defining a'channel between the interiors of chamber 26 and well 22. A second hollow conduit 32 is provided for defining a channel between the interiors of chamber 26 and well 24. Preferably, each of the conduits enter the respective well to which they are coupled through a side wall thereof substantially normal to a tangent at the point of entry. This insures that a certain volume of dielectric material is minimally maintained between the interior of each conduit and the interior of the wells.

In operation, as shown in connection with FIG. 2, a source of electrically conductive paste, typically a squeeze tube 34 is coupled to port 28 by screwing the tube into the port. Pressure on tube 34 ejects paste into chamber 26, completely filling the latter as air within the chamber is displaced by the paste. Continued ejection of the paste from the tube, forces additional quantities of paste through conduits 30 and 32 and out into wells 22 and 24. In order to insure even distribution of the paste to both wells, the conduits are preferably matched in configuration and dimensions thereby evenly dividing the hydraulic pressure driving the paste through them. When the bottom portion of the two wells have a substantial amount of paste in them it will be apparent that the paste in the conduits and the central chamber form a continuous, electrically-conductive path between the two wells. Normally such electrically conductive pastes typically have low specific electrical resistivities. However, by making the two conduits tortuous in configuration, thereby extending their length without extending the spacing of the wells to an inconvenient distance from one another, the electrode paste filling the conduits and central chamber can constitute a substantially high resistive impedance (preferably 100Q) between the two wells.

When the two defibrillator paddles 36 and 37 are in storage position, i.e. respectively in the wells so that their electrically conductive surfaces contact the paste, pressure applied to the paste by the weight of the paddles thereby forces the paste in the wells (if in sufiicient quantity) to be distributed substantially evenly across the entire electrically conductive surface of each paddle. The paddles in storage position are thus always properly coated for immediate application in the event of an emergency. Thus, the stand serve then to provide a reservoir of paste for the paddles. When the paddles are emplaced in their storage position in the wells and are coupled to defibrillator 38, if the latter is turned on and allowed to discharge, the comparatively high-resistance conductive path between the wells, i.e. through the paste in the conduits and central chamber, constitutes a load resistor capable of dissipating the energy of the discharge without injuring the defibrillator. The operativeness of the defibrillator can be determined by examining meter 40 of defibrillator 38 to observe the defietcion of the meter needle during discharge through the paste path. Immediately thereafter, if the defibrillator is in operative condition, the paddles can be removed from the stand and used for treatment of the patient without further preparation.

In the preferred embodiment of the present invention there are several additional features which are quite desirable. For example, as shown in FIGS. 3 and 4 in which well 22 is exemplary also of well 24, each well includes a peripheral groove 42 disposed around the inner wall of the well so as to provide a small overhang or lip 44. Disposed within groove 42 is flexible O-ring seal 46. The diameter and cross-section configuration of the well is tailored to the size and shape of the particular paddle intended to be stored therein, the internal diameter of the weli being preferably larger than the diameter of the typical circular paddle surface. The O-ring has a slightly smaller inside diameter than the well diameter, and is intended to fit quite snugly about the circumference of the paddle surface. Thus, the O-ring and the grooved configuration of the well serves as means for minimizing evaporation of fluid from paste disposed within the well underneath the emplaced paddle.

As will also be seen in FIGS. 3 and 4, bottom 48 of the well is preferably shaped to conform to the contour of the electrically conductive surface of the paddle and is, therefore, typically fiat. However, in the preferred embodiment conduit 30 enters through the well wall preferably slightly below the bottom 48, the latter being provided with a series of open grooves or channels 50 which join one another adjacent the entrance point of conduit 30 into the well. The purpose of flow channels 50 is to provide a network which serves to distribute paste ejected from conduit 30 more evenly across the bottom of the well. This network of channels, when filled with conductive paste, provides a distribution system for current passing between paste in conduit 30 and the paddle surface in contact with the paste in the well. If a concentration of current occurs in paste adjacent the entrance point of conduit 30 into the well, there is a possibility that an arc will be struck between the conductive surface of the paddle and the paste at the entrance point during discharge from the defibrillator. While such arcing is not serious, it is disconcerting, and repetitive arcing will heat the paste, tending to drive olT fluid so as to dry the paste.

While the stand of the invention has been described as comprising slab 20, it is difficult to form tortuous conduits therein without incurring substantial costs. And while it is not necessary to form the structure as an integral unit, it is desirable to keep the elements thereof in connected form. Consequently, it is preferred to form the structure, substantially as shown in FIGS. 5 and 6, from a plurality of layers. Thus, there is a base layer in the form of a substantially flat solid element 52 made of an electrically insulating material such as polymethyl methacrylate. A second flat layer or gasket 54 is bonded, as by an epoxy cement, to the upper surface of element 52 and has conduits 30 and 32 cut therein in the form of channels leading into portions of wells 22 and 24 also cut therein. Lastly, bonded, typically also by epoxy cement, on top of the gasket 54 is top layer 56 having port 28 and chamber 26 cut therein and also having a pair of spaced cutout portions which respectively constitute the remainder of wells 22 and 24. Of course, the cutout portions of upper lay 56 forming the portions of the wells are registered with the corresponding cutout portions of gaskets 54. Port 28 is located so as to provide access to the channels in the gasket. Thus, the side walls of conduits 30 and 32 are respectively formed by gasket 54 and the top and bottom of each of the conduits are respectively formed by top layer 56 and element 52. This modification of the structure is easier to manufacture, and in addition, in the preferred embodiment, top layer 56 is formed of a material which is not only electrically insulating, as if, of course, gasket 54, but layer 56 is also preferably transparent. In this form top layer 56 then permits one to visually determine immediately whether or not there is an adequate paste supply to completely fill conduits 30 and 32 so as to constitute the required conductive path between the two wells.

What is claimed is:

1. Apparatus for storing defibrillation paddles coated with conductive paste and for testing the operability of a defibrillator discharge device connected to said paddles, said apparatus comprising in combination;

a pair of spaced apart, containers of electrically nonconductive material, each dimensioned and shaped to hold a quantity of said paste and to support a respective one of said paddles in electrical contact with said paste;

hollow conduit means of electrically non-conductive material and connecting the interior of said containers to one another;

means for connecting a source of said paste to said conduit means; and

said conduit means being so dimensioned that when filled with paste from said source, the electrical resistance through said conduit between said containers constitutes a load resistor capable of dissipating a discharge from said defibrillator device.

2. Apparatus as defined in claim 1 where in said containers are a pair of wells formed in a common surface of a block of non-conductive material, said conduit means extends between said wells through said block, and at least the portion of said block between said conduit means and surface is transparent.

3. Apparatus as defined in claim 1 wherein said conoduits means enters said containers substantially along an axis directed normally to a tangent to the periphery of each of said containers.

4. Apparatus as defined in claim 1 wherein said'conduit means follows a tortuous path between saidcontainers.

5. Apparatus as defined in claim 2 wherein the edge of each of said wells at said surface is formed as a lip extending into said well, said edge being shaped and dimensioned to fit loosely about said paddle, and including a flexible O-ring seal seated below said lip and shaped and dimensioned to fit snugly around said paddle.

6. Apparatus as defined in claim 2 wherein the bottom of each of said wells bears a plurality of grooves joining at a common point adjacent the point of entry of said conduit means into said well.

References Cited UNITED STATES PATENTS EDWARD E. KUBASIEWICZ, Primary Examiner I. M. HANLEY, Assistant Examiner US. Cl. X.R. 128-206 

